U.S. Pat. No. 4,789,801 issued to Lee, and incorporated herein by reference, describes various devices to generate a stream of ionized air using an electro-kinetic technique. In overview, electro-kinetic techniques use high electric fields to ionize air molecules, a process that produces ozone (O3) as a by product. Ozone is an unstable molecule of oxygen that is commonly produced as a by product of a high voltage arcing. In appropriate concentrations, ozone can be a desirable and useful substance. But ozone by itself may not be effective to kill microorganisms such as germs, bacteria, and viruses in the environment surrounding the device.
FIG. 1 depicts a generic electro-kinetic device 10 to condition air. Device 10 includes a housing 20 that typically has at least one air input 30 and at least one air output 40. Within housing 20 there is disposed an electrode assembly or system 50 comprising a first electrode array 60 having at least one electrode 70 and comprising a second electrode array 80 having at least one electrode 90. System 10 further includes a high voltage generator 95 coupled between the first and second electrode arrays. As a result, ozone and ionized particles of air are generated within device 10, and there is an electro-kinetic flow of air in the direction from the first electrode array 60 towards the second electrode array 80. In FIG. 1, the large arrow denoted IN represents ambient air that can enter input port 30. The small “x”'s denote particulate matter that may be present in the incoming ambient air. The air movement is in the direction of the large arrows, and the output airflow, denoted OUT, exits device 10 via outlet 40. An advantage of electro-kinetic devices such as device 10 is that an airflow is created without using fans or other moving parts. Thus, device 10 in FIG. 1 can function somewhat as a fan to create an output airflow, but without requiring moving parts.
Preferably particulate matter “x” in the ambient air can be electrostatically attracted to the second electrode array 80, with the result that the outflow (OUT) of air from device 10 not only contains ozone and ionized air, but can be cleaner than the ambient air. In such devices, it can become necessary to occasionally clean the second electrode array electrodes 80 to remove particulate matter and other debris from the surface of electrodes 90. Accordingly, the outflow of air (OUT) is conditioned in that particulate matter is removed and the outflow includes appropriate amounts of ozone, and some ions.
An outflow of air containing ions and ozone may not, however, destroy or significantly reduce microorganisms such as germs, bacteria, fungi, viruses, and the like, collectively hereinafter “microorganisms.” It is known in the art to destroy such microorganisms with, byway of example only, germicidal lamps. Such lamps can emit ultra-violet radiation having a wavelength of about 254 nm. For example, devices to condition air using mechanical fans, HEPA filters, and germicidal lamps are sold commercially by companies such as Austin Air, C.A.R.E. 2000, Amaircare, and others. Often these devices are somewhat cumbersome, and have the size and bulk of a small filing cabinet. Although such fan-powered devices can reduce or destroy microorganisms, the devices tend to be bulky, and are not necessarily silent in operation.
U.S. Pat. Nos. 5,879,435, 6,019,815, and 6,149,717, issued to Satyapal et al., and incorporated herein by reference, discloses an electronic air cleaner that contains an electrostatic precipitator cell and a germicidal lamp for use, among other uses, with a forced air furnace system. The electrostatic precipitator cell includes multiple collector plates for collecting particulate material from the airstream. The germicidal lamp is disposed within the air cleaner to irradiate the collector plates and to destroy microbial growth that might occur on the particulate material deposited on the collector plates. Particles that pass through the air cleaner due to the action of the fan of the forced air furnace, and that are not deposited on the collector plates, generally are not subjected to the germicidal radiation for a period of time long enough for the light to substantially reduce microorganisms within the airflow.